5.7.6 Context Declaration Example

Here is a more complex example of with-compilation-unit options:

:optimize '(optimize (speed 2) (space 2) (inhibit-warnings 2)
                     (debug 1) (safety 0))
:optimize-interface '(optimize-interface (safety 1) (debug 1))
:context-declarations
'(((:or :external (:and (:match "@%") (:match "SET")))
   (declare (optimize-interface (safety 2))))
  ((:or (:and :external :macro)
        (:match "$PARSE-"))
   (declare (optimize (safety 2)))))

The optimize and extensions:optimize-interface declarations (see optimize-declaration) set up the global compilation policy. The bodies of functions are to be compiled completely unsafe (safety 0), but argument count and weakened argument type checking is to be done when a function is called (speed 2 safety 1).

The first declaration specifies that all functions that are external or whose names contain both “@%” and “SET” are to be compiled compiled with completely safe interfaces (safety 2). The reason for this particular :match rule is that setf inverse functions in this system tend to have both strings in their name somewhere. We want setf inverses to be safe because they are implicitly called by users even though their name is not exported.

The second declaration makes external macros or functions whose names start with “PARSE-” have safe bodies (as well as interfaces). This is desirable because a syntax error in a macro may cause a type error inside the body. The :match rule is used because macros often have auxiliary functions whose names begin with this string.

This particular example is used to build part of the standard CMUCL system. Note however, that context declarations must be set up according to the needs and coding conventions of a particular system; different parts of CMUCL are compiled with different context declarations, and your system will probably need its own declarations. In particular, any use of the :match option depends on naming conventions used in coding.